Magenta is the complement of green, and yellow the complement of blue. Ideally, the cyan is completely transparent to green and blue light and has no effect on those parts of the spectrum.

The amount of cyan applied to a white sheet of paper controls how much of the red in white light will be reflected back from the paper. Cyan is the complement of red, meaning that the cyan serves as a filter that absorbs red. In color printing, the usual primary colors are cyan, magenta and yellow (CMY). In late 19th and early to mid-20th-century commercial printing, use of the traditional RYB terminology persisted even though the more versatile CMY (cyan, magenta, yellow) triad had been adopted, with the cyan sometimes referred to as 'process blue' and the magenta as 'process red'.ĬMY and CMYK color models and printing processes

These ideas and many personal color observations were summarized in two founding documents in color theory: the Theory of Colours (1810) by the German poet and government minister Johann Wolfgang von Goethe, and The Law of Simultaneous Color Contrast (1839) by the French industrial chemist Michel Eugène Chevreul. These theories were enhanced by 18th-century investigations of a variety of purely psychological color effects, in particular, the contrast between 'complementary' or opposing hues produced by color afterimages and in the contrasting shadows in colored light. The RYB primary colors became the foundation of 18th-century theories of color vision as the fundamental sensory qualities blended in the perception of all physical colors and equally in the physical mixture of pigments or dyes. The resultant spectral power distribution is predicted by sequentially taking the product of the spectral power distributions of the incoming light and transmissivity at each filter. Each layer partially absorbs some wavelengths of light from the illumination spectrum while letting others pass through, resulting in a colored appearance. The subtractive color mixing model predicts the resultant spectral power distribution of light filtered through overlaid partially absorbing materials on a reflecting or transparent surface. This idealized model is the essential principle of how dyes and inks are used in color printing and photography where the perception of color is elicited after white light passes through microscopic 'stacks' of partially absorbing media allowing some wavelengths of light to reach the eye and not others. Subtractive color or subtractive color mixing predicts the spectral power distribution of light after it passes through successive layers of partially absorbing media. The overlapping subtractive yellow, cyan and red (magenta) image elements can be seen clearly along the edges of the image. An 1877 color photo by Louis Ducos du Hauron, a French pioneer of color photography.

Primary colors in the color wheel